From 0976267f0f4c27cd61cd88041d68d3465a8f9d86 Mon Sep 17 00:00:00 2001
From: Andy Goldstein <andy.goldstein@redhat.com>
Date: Tue, 18 Oct 2022 16:34:28 -0400
Subject: [PATCH] Make empty unstructured check common

Move the empty unstructured object check from the webhook converter to
the delegating converter, so other converters don't have to repeat the
same logic.

Signed-off-by: Andy Goldstein <andy.goldstein@redhat.com>
---
 .../pkg/apiserver/conversion/converter.go     | 27 ++++++++++++++++++
 .../apiserver/conversion/webhook_converter.go | 28 -------------------
 2 files changed, 27 insertions(+), 28 deletions(-)

diff --git a/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/conversion/converter.go b/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/conversion/converter.go
index aafe44f87c3..89600d1b6fb 100644
--- a/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/conversion/converter.go
+++ b/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/conversion/converter.go
@@ -179,6 +179,7 @@ func (c *delegatingCRConverter) ConvertToVersion(in runtime.Object, target runti
 		// TODO: should this be a typed error?
 		return nil, fmt.Errorf("%v is unstructured and is not suitable for converting to %q", fromGVK.String(), target)
 	}
+
 	// Special-case typed scale conversion if this custom resource supports a scale endpoint
 	if c.convertScale {
 		if _, isInScale := in.(*autoscalingv1.Scale); isInScale {
@@ -204,6 +205,13 @@ func (c *delegatingCRConverter) ConvertToVersion(in runtime.Object, target runti
 			}
 		}
 	}
+
+	// A smoke test in API machinery calls the converter on empty objects during startup. The test is initiated here:
+	// https://github.com/kubernetes/kubernetes/blob/dbb448bbdcb9e440eee57024ffa5f1698956a054/staging/src/k8s.io/apiserver/pkg/storage/cacher/cacher.go#L201
+	if isEmptyUnstructuredObject(in) {
+		return NewNOPConverter().Convert(in, toGVK.GroupVersion())
+	}
+	
 	return c.converter.Convert(in, toGVK.GroupVersion())
 }
 
@@ -232,3 +240,22 @@ func (c *safeConverterWrapper) Convert(in, out, context interface{}) error {
 func (c *safeConverterWrapper) ConvertToVersion(in runtime.Object, target runtime.GroupVersioner) (runtime.Object, error) {
 	return c.unsafe.ConvertToVersion(in.DeepCopyObject(), target)
 }
+
+// isEmptyUnstructuredObject returns true if in is an empty unstructured object, i.e. an unstructured object that does
+// not have any field except apiVersion and kind.
+func isEmptyUnstructuredObject(in runtime.Object) bool {
+	u, ok := in.(*unstructured.Unstructured)
+	if !ok {
+		return false
+	}
+	if len(u.Object) != 2 {
+		return false
+	}
+	if _, ok := u.Object["kind"]; !ok {
+		return false
+	}
+	if _, ok := u.Object["apiVersion"]; !ok {
+		return false
+	}
+	return true
+}
diff --git a/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/conversion/webhook_converter.go b/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/conversion/webhook_converter.go
index 3cb05cef5b4..f89cf448de6 100644
--- a/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/conversion/webhook_converter.go
+++ b/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/conversion/webhook_converter.go
@@ -229,15 +229,6 @@ func getConvertedObjectsFromResponse(expectedUID types.UID, response runtime.Obj
 
 func (c *webhookConverter) Convert(in runtime.Object, toGV schema.GroupVersion) (runtime.Object, error) {
 	ctx := context.TODO()
-	// In general, the webhook should not do any defaulting or validation. A special case of that is an empty object
-	// conversion that must result an empty object and practically is the same as nopConverter.
-	// A smoke test in API machinery calls the converter on empty objects. As this case happens consistently
-	// it special cased here not to call webhook converter. The test initiated here:
-	// https://github.com/kubernetes/kubernetes/blob/dbb448bbdcb9e440eee57024ffa5f1698956a054/staging/src/k8s.io/apiserver/pkg/storage/cacher/cacher.go#L201
-	if isEmptyUnstructuredObject(in) {
-		return c.nopConverter.Convert(in, toGV)
-	}
-
 	listObj, isList := in.(*unstructured.UnstructuredList)
 
 	requestUID := uuid.NewUUID()
@@ -451,22 +442,3 @@ func restoreObjectMeta(original, converted *unstructured.Unstructured) error {
 
 	return nil
 }
-
-// isEmptyUnstructuredObject returns true if in is an empty unstructured object, i.e. an unstructured object that does
-// not have any field except apiVersion and kind.
-func isEmptyUnstructuredObject(in runtime.Object) bool {
-	u, ok := in.(*unstructured.Unstructured)
-	if !ok {
-		return false
-	}
-	if len(u.Object) != 2 {
-		return false
-	}
-	if _, ok := u.Object["kind"]; !ok {
-		return false
-	}
-	if _, ok := u.Object["apiVersion"]; !ok {
-		return false
-	}
-	return true
-}